Rush Limbaugh, while repeatedly insisting he is “not alleging a conspiracy,” suggested Monday that the National Hurricane Center’s forecast models for Tropical Storm Isaac were altered to help President Barack Obama and “cast a pall” over the Republican National Convention.

“I’m not alleging conspiracies here. The Hurricane Center is the regime; the Hurricane Center is the Commerce Department,” Limbaugh said on his talk show. “It’s the government. It’s Obama.”

The conservative talker suggested early forecasts, which showed the storm hitting Tampa, the convention’s host city, were intended to cause Republicans to cancel the first day of their convention. Newer models showing the storm striking New Orleans, he said, are intended to link the convention to memories of Hurricane Katrina, which made landfall seven years ago this week.

In between the models showing the storm striking Tampa and the models showing the storm striking New Orleans, Limbaugh claimed there was “one of the biggest, one of the largest shifts in model forecast I have seen since 1997 when I moved down [to Florida] and started caring about this stuff.”

“I know full well that if you give these people the slightest chance and they’re gonna turn this into Katrina and they’re gonna scare the hell out of New Orleans and they’re gonna revive, ‘Bush doesn’t care about people’ and revive all of it,” Limbaugh said, according to a transcript. “They’re gonna politicize everything ’cause they do it. And now they had the model runs allowing them to do it.”

A spokesman for the National Hurricane Center hasn’t responded to an email seeking comment.